A link interconnect allows communication between devices and functional blocks. Some examples of interconnects are shared buses and point to point links. A slotted ring interconnect consists of a fixed number of slots arranged in a closed loop. Each ring slot is either empty, or occupied by a message. The ring may rotate either clockwise or counterclockwise. That is, a message in a slot may travel around the ring in either clockwise or counterclockwise direction. The direction of rotation does not matter. The basic operation of the ring is simple: at each clock, the content of each slot is typically replaced by that of its upstream neighbor (e.g., the counterclockwise neighbor if the ring rotation is clockwise). Essentially, the whole ring can be thought of as a circular shift register.
Typically, a subset of the slots on a ring has one or more stations attached to them. All of the slots on a ring, however, may have one or more stations attached. A station can send and receive messages via the slot to which it is attached. To send a message, a station waits for its attached slot to become empty and, when that happens, puts the message it wishes to send in the slot. Typically, each message carries the identification of the station to which it is destined.
Generally, a station keeps monitoring its attached slot for messages targeting it. When a message arrives, the station removes the message from the slot if it has the necessary resource for receiving it. Whether a station can receive and send in the same clock depends on implementation details and is not relevant to the present invention.